Generate Unique ID from Alphanumeric String

Question

I need to generate a UNIQUE id (int only) from an Alphanumeric string.

e.g. I have security id = 'ABC123DEF' I should be able to generate an unique ID (int only) of "security id" so that the unique ID is always constant.

e.g. Security ID : ABC123DEF Int ID : 9463456892

So that I can store the Int ID in Database and refer the security ID from Int ID anytime.

Some Examples: PBG_CD_20120214_.2 | 201202-CMG188963_T | PBG_TD_20120306_.0001 3 examples :-PIPE seperated

Gap

You're very specific it must be an int, but please define int? The number you put is too large for a traditional int which refers to 32-bits usually, though fits in a long. What are the space contraints of the numeric ID? – Select

Hi Jimmy Its can be Long int. May be i should put in this way. The generated ID should be in "Numberic (0 - 9)" – Gap

Answer 1

Just use the Java hashing algorithm. Not 100% unique but you can use it as a base and add something to guarantee uniqueness on a much smaller collision set:

public static int hash(String s) {
    int h = 0;
    for (int i = 0; i < s.length(); i++) {
        h = 31 * h + s.charAt(i);
    }
    return h;
}

In order to avoid collision 100%, you need a prime number that is bigger than the wider difference between your characters. So for 7-bit ASCII, you need something higher than 128. So instead of 31, use 131 (the next prime number after 128). The part I haven't checked is if the generated hash will wind up being bigger than the size of your long ints. But you can take it from there...

Pontus

Don't forget to approve the answer for the benefit of the community if it works – Pontus

Elegant solution! Ported it in maxscript (3dsmax scripting), tested it and so far i didn't have any collision. This is gem! – Caligula

Answer 2

You could encode each character as a two-digit number, 0-9 as the numbers themselves, 10-35 as A-Z.

For example, 9AC8 would be 09 10 12 08 = 09101208.

EDIT: For a small number you could use this approach (with Java-style pseudocode):

char[] availableChars = ['A', 'B', ... , '0', ... '9', '-', '_', '.'];
long hash = 0;
long base = 1;
for (char c in string.toCharArray())
    for (int key=0; key < availableChars.length; key++)
        if (availableChars[key] != c)
            continue;
        hash += base*key;
        base = base*availableChars.length

return hash;

Abernathy

I have an Alphanumeric String : Like "201202-CMG277440_T" – Gap

Is there a limit to how large your numbers can be? – Abernathy

No - No Limit on how large the number can be. – Gap

Then if you had two additional numbers for the hyphen and underscore, this algorithm will work. If you need smaller numbers, I have a suggested solution as well – Abernathy